Recent rapid development of networks including Internet has brought about circulations of various contents (hereinafter, represented by contents) such as music, images, videos, and software (application programs) via the network, digital broadcast network, etc.
Some of such contents make sole use thereof unable through encryption of the contents to avoid unauthorized use of the contents. The authorized user has a license, decodes the content based on information contained in the license, and is able to use the content in conformity with use conditions contained in the license.
In relation to the content use control, Patent Document 1, for example, discloses a content use control device. The content use control device performs use control of a content provided from an authorized information providing source to the user and includes use unit to which is imparted identification information about a physical element making up the use unit itself and use control unit that controls use of the content based on the identification information imparted to the use unit and on permission information about use of the content, with a recording medium having thereon recorded the permission information associated with the content. The use control unit controls use of the content based on the permission information acquired from the recording medium and on the identification information. When use is permitted, the use unit acquires a content from the recording medium for subsequent use of the content.
Referring to FIG. 32, description will now be made of the conventional relationship between the content and the license disclosed in the Patent Document 1.
FIG. 32 is a diagram explaining the conventional relationship between the content and the permission information (license information). A content 101 and permission information (hereinafter, referred to as a license) 102 are stored in an MO medium in an associated manner as shown in FIG. 32. In the MO medium, the content 101 is divided into three contents, i.e., a content(1/3) 1011, a content(2/3) 1012, and a content(3/3) 1013. The content (1/3)1011, content (2/3)1012, and content (3/3)1013 are stored into respective regions designated respectively by LBN (Logical Block Number)=L, LBN=M, and LBN=N.
Similarly, in the MO medium, the license 102 is divided into two licenses, i.e., a license(1/2) 1021 and a license(2/2) 1022. The license(1/2) 1021 and license (2/2) 1022 are stored into respective regions designated respectively by LBN=X and LBN=Y. The content 101 and the license 102 are associated with each other via file management data DA1 and auxiliary file management data DA2. The file management data DA1 are data for managing the content 101 constituting a file main body and the license 102 constituting an auxiliary file. The file management data DA1 are constructed of information containing ‘file name’, ‘date of creation’, . . . , ‘link to auxiliary file management data’, ‘link to file main body (1/3)’, ‘link to file main body (2/3)’, and ‘link to file main body (3/3)’. On the other hand, the auxiliary file management data DA2 are data for directly managing the license 102 and are constructed of information containing ‘auxiliary file name’, ‘date of creation” , . . . , ‘link to license (1/2)’ and ‘link to license (2/2)’.
In digital broadcasting such as BS digital broadcasting, CS digital broadcasting and terrestrial broadcasting, a TS (Transport Stream) obtained by multiplexing MPEG-2 ESs (Elementary Streams) is transmitted with use conditions (e.g., copy control information) of each ES being recorded in the stream. For this reason, the use conditions of the streams having digital broadcasting recorded therein could not be recognized until the stream is reproduced. In Patent Document 2, to solve this respect, copyright information extracted from the stream is associated with the original streams and recorded so that the information can be read out without reproduction of the stream. In case of using the original streams, the recorded copyright information is referred to so that a control is provided in conformity thereto.
Patent Document 3, for example, discloses a technique pertaining to license control for use in data distribution system. That is, the use conditions contained in the license include reproduction control information restricting output count of reproduced information (therefore reproduction count of a content can be restricted) and duplication restriction information restricting the duplicable count of the reproduction control information (therefore duplication count of a content can be restricted), as well as transfer restriction information restricting the transferable number of times.
On the contrary, since a content is important to the user, a write-protect technique is widely employed in order not to inadvertently delete the content. Although not explicitly specified as documents, an example thereof is write-protect unit (so-called a write-protect lever) disposed on a VHS video tape.
While the write-protect unit of the VHS video tape are specified with hardware, there exists a technique specifying the write-protect with software.
For example, Patent Document 4 discloses a hard disk device incorporating write-protect information for the entire hard disk device.
FIG. 33 is a block diagram of a configuration of the conventional hard disk device incorporating the write-protect information, in which reference numeral 110 denotes a hard disk which consists of an interface circuit 111, a read/write channel 112, a write-protect storage memory 113, and a head 114. The write-protect information for the entire hard disk 110 is recorded in the write-protect storage memory 113 and is referred to when accepting a writing request from the interface circuit 111. When the write-protect is on, writing inhibit status comes into existence. When the write-protect is off, a writing instruction is issued via the read/write channel 112 to the head 114 for writing operation.
A technique is also disclosed in Patent Document 5 for setting/canceling the write-protect for each of contents by setting/canceling the write-protect status for each of the regions where the contents are recorded.    Patent Document 1: Japanese Laid-Open Patent Publication No. 2001-092721    Patent Document 2: Japanese Laid-Open Patent Publication No. H10-210411    Patent Document 3: International Publication No. WO01/043342    Patent Document 4: Japanese Laid-Open Patent Publication No. 2000-173158    Patent Document 5: Japanese Laid-Open Patent Publication No. 2002-288933